1. Field of the Invention
The present invention relates to a seat structure for a vehicle (which is referred to a "vehicle seat structure", hereinafter) comprising a connecting member which connects a reclining apparatus at a widthwise direction outer side of a vehicle seat and a reclining apparatus at the widthwise direction inner side of the vehicle seat to interlock the reclining apparatuses with one another, and a reinforcing member which is tubular and provided adjacent to the connecting member, each end portion of the reinforcing member being fixed to the corresponding structural member of the respective reclining apparatus (hereinafter, the widthwise direction outer side will be referred to simply as the outer side, and the widthwise direction inner side will be referred to simply as the inner side).
2. Description of the Prior Art
Conventionally, various countermeasures have been taken against a side collision of a vehicle (which is referred to a "side collision" hereinafter when it is necessary). From a stand point of the vehicle seat structure, in general, such countermeasures have been taken in which rigidity of the vehicle seat structure is reinforced by increasing thicknesses of plates of a seat back frame which forms a main structure of a seat back and a seat cushion frame which forms a main structure of a seat cushion, and that supporting rigidity against a side collision load which acts on a vehicle is improved by adding a plurality of reinforcements to the vehicle seat structure. However, there exists a drawback in that thicknesses of plates of the seat back frame and the seat cushion frame as well as the number of structural members which are used for the vehicle seat structure are increased and the weight of the vehicle seat is increased accordingly.
Thus, methods of a vehicle seat structure in which a tubular member is disposed along the widthwise direction of the vehicle seat and prevents the aforementioned demerit such as the increase in the weight of the vehicle seat or the like have been disclosed (e.g. in U.S. Pat. Nos. 4,231,607, 5,407,244, and 5,507,554, etc.). A description of vehicle seat structures as disclosed in the publications of U.S. Pat. Nos. 5,407,244 and 5,507,554 will be given in detail hereinafter.
A schematic front view of a front seat 100 for a driver's seat is shown in FIG. 11. As shown in this figure, the front seat 100 is comprised of a seat cushion 102, a seat back 106 which is disposed in a upright state at the rear end portion of the seat cushion 102 and which can be tilted by a reclining apparatus 104, and a headrest 108 which is provided at the upper end portion of the seat back 106 and which can be adjusted to move in the upper and lower directions thereof.
A seat sliding apparatus 110 is provided at the lower end portion of the seat cushion 102. The seat sliding apparatus 110 is comprised of a pair of lower rails 116 which are fixed to a floor panel 112 via a pair of brackets 114, and a pair of upper rails 118 which are provided at the lower end portion of the seat cushion 102 and which are fitted into the lower rails 116. Accordingly, although the front seat 100 is slidable in the longitudinal direction of a vehicle, in the widthwise direction of the vehicle, the front seat 100 is supported to be immobilized.
A seat back frame 120 which serves as a frame of the seat back 106 is frame-shaped. A singular and tubular reinforcing member 122 is disposed at a lower end portion 120A of the seat back frame 120 via a pair of brackets 124. The longitudinal direction of the reinforcing member 122 is along with the widthwise direction of the seat back 106. A load input portion 126 and a load output portion 128 having a disc-shaped configuration are fixed to each end portion of the reinforcing member 122, respectively. The load input portion 126 and the load output portion 128 are disposed in vicinities of reclining lower arms 130, which form a part of the reclining apparatus 104, and are disposed at the rear end and widthwise direction ends of the seat cushion 102. A predetermined interval is provided between the load input portion 126 and one of the reclining lower arms 130, and between the load output portion 128 and the other reclining lower arm 130.
According to the aforementioned structure, as shown in FIG. 12, when a side door 132 of a vehicle at a normal position (i.e., the position is drawn by a dual dotted broken line) is hit by a front bumper 136 of another vehicle body 134, the side door 132 is deformed toward a vehicle interior side (i.e., from a position indicated by the dual dotted broken line to a position indicated by a single dotted broken line). For this reason, the inner panel of the side door 132 abuts the external end portion of the reclining apparatus 104 of the front seat 100, and the reclining lower arm 130 is displaced and abuts the load input portion 126. Therefore, the reinforcing member 122 is displaced toward a reinforced console box 138 side or a floor tunnel 200 side (i.e., inwardly in the transverse direction of the vehicle), so that the load output portion 128 is caused to abut the other reclining lower arm 130 (which is disposed inwardly of the vehicle in the widthwise direction thereof). In this way, the side collision load, while being absorbed and decreased, is transmitted to the reinforced console box 138 side to a front passenger seat through the reinforcing member 122, finally to a floor panel 112 and the side collision load is thereby absorbed. As a result, the crash of the front seat 100 in the widthwise direction of the vehicle seat is prevented.
However, when the side collision load input to the reinforcing member 122 through the load input portion 126 is larger than the buckling load of the reinforcing member 122, it is possible that the reinforcing member 122 bends largely at the longitudinal central portion thereof. However, according to the aforementioned vehicle seat structure, because the deformation direction of the reinforcing member 122 is not specified, depending on the cases, the reinforcing member 122 may deform toward the vehicle occupant side to reduce the seating space of the vehicle occupant.